In order to facilitate group communication, conflict resolution, and overall project completion, our group has created the following roles and assigned group members to them based on the information provided in the self evaluation.

In order to facilitate group communication, conflict resolution, and overall project completion, our group has created the following roles and assigned group members to them based on the information provided in the self evaluation.

−

'''Project Manager (Ethan George)'''- The project manager will be responsible for assigning work to other group members as well as laying out a timeline for meetings. In addition to taking some tasks for himself, he will contact other group members regularly to make sure they are moving at a proper pace and try to prevent parts of the project from being overlooked. In addition, he will make the final decision on issues such as requirement interpretation, group conflicts, changes of schedule, and whether work submitted by other members is of high enough quality or not.

+

'''Project Manager (Ethan George)'''- The project manager will be responsible for assigning work to other group members as well as laying out a timeline for meetings. In addition to taking some tasks for himself, he will contact other group members regularly to make sure they are moving at a proper pace and try to prevent parts of the project from being overlooked. In addition, he will make the final decision on issues such as requirement interpretation, changes of schedule, and whether work submitted by other members is of high enough quality or not.

'''Communication Liaison (Michael Halloran)'''- The communication liaison will be responsible for being a reliable point of contact with the professors, as well as organizing and posting the group’s work through the wiki page. He will disseminate any information or feedback the professors provide and ask any questions the group has. Below, the contact information for the communication liaison is listed again:

'''Communication Liaison (Michael Halloran)'''- The communication liaison will be responsible for being a reliable point of contact with the professors, as well as organizing and posting the group’s work through the wiki page. He will disseminate any information or feedback the professors provide and ask any questions the group has. Below, the contact information for the communication liaison is listed again:

Line 179:

Line 179:

'''Research Experts (Takur Phuyel and Tharaka Gabadage)'''- The research experts will be responsible for doing any research not already covered by the technical expert. In addition to completing tasks that are specifically research oriented, they will also look into any other questions that may arise over the course of the project. They will then be responsible for informing the group about their findings so that the entire group will have a clearer understanding of the project.

'''Research Experts (Takur Phuyel and Tharaka Gabadage)'''- The research experts will be responsible for doing any research not already covered by the technical expert. In addition to completing tasks that are specifically research oriented, they will also look into any other questions that may arise over the course of the project. They will then be responsible for informing the group about their findings so that the entire group will have a clearer understanding of the project.

+

+

===Conflict Resolution Plan===

+

All group conflicts will be settled by a discussion of the disagreement at either the next meeting or a meeting scheduled by the project manager to specifically deal with urgent issues. Once the conflict has been discussed other group members will be allowed to suggest alternative solutions, and all group members will then vote on the course of action they most prefer. Individuals who ignore group decisions, do not complete the required work, or fail to attend meetings without a legitimate excuse will be worked around by delegating all significant assignments to other group members. As recourse the other group members will collectively give such individuals poor scores on the group evaluation at the end of the project.

=Product Archaeology=

=Product Archaeology=

+

This section contains our group's findings after performing background research on our product and performing an inspection without completing disassembly.

==Development Profile==

==Development Profile==

+

[[File:Flex-tools.png|300px|thumb|right|The first angle grinder developed by Flex Company consisted of an electric motor and a flexible shaft for grinding attachments.]]

+

The first angle grinder was developed by Flex Company in the late 1920s. While this angle grinder does not bear much resemblance to modern angle grinders, it was the first handheld tool to allow the user to perform grinding functions. The DeWalt Heavy Duty Angle Grinder family of products was later developed in the early 2000s (Flex-Tools.com). At this point in time the primary global and economic concerns for the angle grinder were the functionality and price point for the intended audience. These concerns are listed below:

−

''When was the product developed?''

+

*Global: The DeWalt angle grinder was developed for countries with developed economies. The tasks angle grinders are intended to do, such as finishing wood, polishing doors, and removing weld seams, are not usually done in developing nations. In addition, a lack of reliable power grid would make the electric angle grinder inferior to those with other power sources.

+

*Economic: The DeWalt angle grinder reduced cost by using less cast iron than traditional angle grinders and replacing many auxiliary parts with plastic. It also uses less power than other similar angle grinders in order to reduce electrical costs for the user. (cpometabo.com)

−

The first angle grinder was developed by Flex Company in the late 1920s. The DeWalt Heavy Duty Angle Grinder family of products was developed in the early 2000s.

−

''What were the key economic and global concerns at the time of the development?''

+

Our angle grinder is only intended for sale in North America, primarily the U.S. and Canada. This is because the product must undergo special testing for certification to be sold in Europe, and “DeWalt Europe” is a similar but different version of this product for sale there. (Blackanddecker.com)

−

Global: The DeWalt angle grinder was developed for countries with developed economies. The tasks angle grinders are intended to do, such as finishing wood, polishing doors, and removing weld seams, are not usually done in developing nations. In addition, a lack of reliable power grid would make the electric angle grinder inferior to those with other power sources.

+

The angle grinder was designed to make many household tasks easier. This product furthers that goal of the original angle grinders by making the angle grinder lighter weight and easier to use, which is ideal for both household use and extended use in a professional setting. The overall intended impact of this product was therefore to make grinding an easier task to accomplish.

−

+

−

Economic: The DeWalt angle grinder reduced cost by using less cast iron than traditional angle grinders and replacing many auxiliary parts with plastic. It also uses less power than other similar angle grinders in order to reduce electrical costs for the user.

+

−

+

−

''In what countries or regions is the product intended to be sold?''

+

−

+

−

Our angle grinder is only intended for sale in North America, primarily the U.S. and Canada. This is because the product must undergo special testing for certification to be sold in Europe, and “DeWalt Europe” a similar but different version of this product for sale there.

+

−

+

−

''What was the intended impact on the consumer and the society in which it is used?''

+

−

+

−

The angle grinder was designed to make many household tasks easier. This product furthers that goal of the original angle grinders by making the angle grinder lighter weight and easier to use, which is ideal for household use.

+

==Usage Profile==

==Usage Profile==

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[[File:Deck_Sanding.jpeg|300px|thumb|right|This user is using an angle grinder to sand a deck much faster than could be done with sand paper.]]

+

The intended use of the angle grinder is grinding various materials. In addition to grinding, multiple attachments can be fitted allowing the angle grinder to cut, sand, and polish. In combination with the ability to use a grinder almost anywhere, these array of functions make the angle grinder a great "all-purpose tool" for material removal. Angle grinders can be used for both home and professional uses, but this angle grinder was most likely designed with an emphasis on professional use. This is because the parent company of DeWalt (Black and Decker) already produces an array of cheaper product alternatives. DeWalt is instead a more expensive heavy duty brand, which suggests the intended customers were either professionals or home owners with hobbies (i.e. carpentry) that required a large amount of grinding.

−

''What is the intended use of the product?''

+

The following is a list of the most common functions an angle grinder might perform in a professional setting.

−

+

* With the use of various qualities of grinding disk an angle grinder can grind metal weld seams to make them smooth.

−

The intended use of the angle grinder is grinding various materials. In addition to grinding, multiple attachments can be fitted allowing the angle grinder to cut, sand, and polish, making this a very useful tool.

+

*Cutting metal, concrete, and stone can be done by attaching a cut-off disk (usually with a diamond blade).

−

+

*Sanding disks allow the user to sand wood quicker than with sand paper.

−

''Is this product for home or professional use?''

+

*Polishing disks and wire brush disks allow the user to polish metal and remove corrosion, rust, and paint from metal.

−

+

−

Angle grinders can be used for both home and professional uses, however the smaller angle grinder our group has is intended primarily for home use.

+

−

+

−

''What jobs does the product perform?''

+

−

+

−

• The main job an angle grinder performs is grinding metal weld seams to make them smooth.

+

−

+

−

• Grinding and cutting metal, concrete and stone can be done by attaching a cut-off disk (usually with a diamond blade).

These functions, along with other more obscure uses, are what make the angle grinder so versatile. It is one tool that allows the user to perform a wide array of tasks for a given job.

+

(All information for this section taken from Blackanddecker.com)

==Energy Profile==

==Energy Profile==

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The product uses AC electrical energy and rotational kinetic energy, which changes direction at the grinder head. Electricity is the only energy imported into the system, which is done by connecting the plug to any standard U.S. AC outlet. The electrical energy imported into the system is then transformed into rotational kinetic energy by an AC motor in the bottom of the tool. This motor drives the main shaft which in turn rotates a gear. This gear redirects the rotational kinetic energy by turning the axis of rotation 90º at the head of the grinder, which in turn delivers its rotational kinetic energy to the grinder’s disk and the object the tool is being used on. This flow of energy is summarized below in Figure 2.

Electricity is the only energy imported into the system, which is done by connecting the plug to any standard U.S. AC outlet.

+

−

+

−

''How are different types of energy transformed and modified?''

+

−

+

−

The electrical energy imported into the system is transformed into rotational kinetic energy by an AC motor in the bottom of the tool. This motor drives the main shaft which in turn rotates a gear. This gear redirects the rotational kinetic energy by turning the axis of rotation 90º at the head of the grinder, which in turn delivers its rotational kinetic energy to the grinder’s disk and the object the tool is being used on.

+

==Complexity Profile==

==Complexity Profile==

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''How many components are used?''

+

Based on observation of the product, group members' collective experience with electronic motors, and our theory of how the angle grinder will work, we have determined that the following components are present in our product. Components in regular font are observable, and therefore definitely present in the product. Components in '''Bold''' are not clearly visible, but our reasons for believing these components are present is given alongside the component.

−

The components our group has observed and theorized are present include:

+

*Power cord

+

*'''Electric Motor''':Based on the presence of a power cord and the fact the grinder outputs kinetic energy, it is safe to assume

+

*'''Main shaft''':There must be some component present to deliver power from the motor to the grinder head. We theorize a shaft is used to carry this energy.

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*Gear box

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*Backing Flange

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*Handle

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*Power Switch

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*Housing

−

• Power cord

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Our method for assessing the complexity of the components was based on the number of parts we theorize will be present and the possible energy flows that may be associated with the component. Each of the components will therefore be rated on the following scale:

+

*'''1''': This component is very simple and only contains one part that either does not contain any energy flows, or only delivers simple energy flows.

+

*'''2''': This component is somewhat complex and may contain multiple parts or contains simple energy flow.

+

*'''3''': This component is very complex and contains multiple parts as well as complicated energy flows.

+

Based on this rating scale, our group has constructed Table 3, which contains all of the observable and theorized parts as well as the complexity of each part and a brief justification for this rating:

−

• Electric Motor

+

<table border=1>

+

<caption>'''Table 3''':Component Complexity</caption>

+

<tr>

+

<th>Component</th>

+

<th>Complexity Rating</th>

+

<th>Justification</th>

+

</tr>

+

<tr>

+

<td>Power Cord</td>

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<td>2</td>

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<td>The power cord consists of at least two parts: the rubber insulation and the copper wire which must branch off to any electrical components at some point. The power cord also allows electricity to flow through it, which is a fairly simple flow of energy.</td>

+

</tr>

+

<tr>

+

<td>Electric Motor</td>

+

<td>3</td>

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<td>The electric motor must consist of several components including magnets, brushes, wire coils, and an armature. There is also a complex flow of energy as the electrical energy input into the system is converted to kinetic energy as an output.</td>

+

</tr>

+

<tr>

+

<td>Main Shaft</td>

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<td>1</td>

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<td>The main shaft would only consist of one part (the shaft) and would deliver a very simple form of energy; it would take rotational energy from the motor and deliver rotational energy to the gearbox.</td>

+

</tr>

+

<tr>

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<td>Gear Box</td>

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<td>3</td>

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<td>The gearbox must contain multiple gears in order to take the rotational energy from the main shaft and turn it 90 degrees. In addition the gearbox must contain ball bearings in order to allow the free rotation of the helical gear. These many parts and the complex flow of energy make the gearbox a very complex component.</td>

+

</tr>

+

<tr>

+

<td>Backing Flange</td>

+

<td>1</td>

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<td>The backing flange only consists of one part and that part only takes rotational energy from the gearbox and delivers it to whatever disk is put on the grinder.</td>

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</tr>

+

<tr>

+

<td>Handle</td>

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<td>1</td>

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<td>The handle is only one piece and does not contain any energy flow.</td>

+

</tr>

+

<tr>

+

<td>Power Switch</td>

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<td>2</td>

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<td>The power switch must consist of at least two parts (the visible switch, and some bar that moves electrical contacts to start the motor). The switch takes a signal from the user and changes it into a signal to start or stop the electric motor. This makes the power switch a moderately complex part.</td>

+

</tr>

+

<tr>

+

<td>Housing</td>

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<td>2</td>

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<td>Even though the housing does not allow for any energy flows, it does contain several pieces that must be assembled properly in order to hold the functional components of the angle grinder in place.</td>

+

</tr>

+

</table>

−

• Main shaft

+

The component interactions can be broken up into three main groups: the electrical interaction, the initial rotational interaction, and the output rotational interaction. These three groups and the complexities of their interactions are given below.

−

• Gear box

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*'''Electrical Interaction''': The electrical component interactions consist of the switch, power cord, and electric motor. Moving the switch results in moving metal contacts that allow energy to flow into the electric motor when the switch is on, but not when it's off. These interactions are simple because they only contain simple energy flows and are very intuitive.

+

*'''Initial Rotational Interaction''': The initial rotational interactions consist of the electric motor, main shaft, and gear box. The electric motor takes the electrical energy supplied by the power cord and converts it into rotational energy by varying the flux in a coil in a magnetic field. This rotational energy is then delivered by the main shaft to the gear box. These component interactions are the most complex as it is the only place in the device where energy completely changes form. A significant part of our investigation of this product will include how these components interact to produce this initial kinetic energy.

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*'''Output Rotational Interaction''': The output rotational interaction consists of the gear box and backing flange. This interaction will be fairly complex as the gearbox must take the rotational energy from the main shaft and redirect it, which will include the interactions of at least two gears. This redirected rotational energy will then be applied to the backing flange, which will then apply the rotational force to whatever attachment is being used on teh angle grinder.

−

• Action Surface

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The remaining components not addressed above do not interact with any other components in ways that contribute to the overall function of the angle grinder (i.e. Handle to housing interaction). The complexity of these component interactions are therefore trivial and non-applicable.

−

+

−

• Handle

+

−

+

−

• Power Switch

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−

+

−

• Housing

+

−

+

−

''How complex are the individual components?''

+

−

+

−

Out of the components listed, only the electric motor and gear box are complex. The electric motor will contain magnets, a wire coil, an armature, and carbon brushes designed to transform the AC electricity into high rpm rotational kinetic energy.

+

−

+

−

The gearbox will contain at least two gears and a bearing that will take the rotational energy from the main shaft and redirect it with minimal kinetic energy loss.

+

−

+

−

All of the other components are simple, consisting of only a few, easily assembled parts.

+

−

+

−

''How complex are component interactions?''

+

−

+

−

The components interact with each other in very simple ways, often only relating to only one or two other parts. The exception is the main shaft, gear box, and action surface. These components have several parts that all work towards the same goal of redirecting the rotational kinetic energy without failing under a load as well as horizontal forces the user may be applying. We do not know exactly how these components will interact yet, but it will probably require additional parts in the gearbox we are unaware of.

Based on coloration, texture, and function where applicable, our group has determined that the clearly visible parts of the angle grinder are made of the following materials:

−

''What materials are clearly visible?''

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*Rubber (cord)

−

+

*Copper (cord wire)

−

• Rubber (cord)

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*Steel (guard and backing flange/interior gear box)

−

+

*Plastic (housing and power switch)

−

• Copper (cord)

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*Aluminum (exterior gear box)

−

+

−

• Steel (guard and wheel nut/screw)

+

−

+

−

• Plastic (housing and power switch)

+

−

''What materials are not visible, but present?''

+

Our group also theorizes that magnetic iron must be present in order for the motor to function. An electric motor is driven by the force of magnetism on a current carrying loop (Experimental Researches in Electricity). All other components that we expect to find will be made of materials already present in the exterior:

−

• Magnetic iron (electric motor)

+

*Main Shaft:

+

**Steel Shaft

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**Copper Wire Coil

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**Plastic Fan

+

*Wires: Copper and Plastic/Rubber insulation

+

*Gears: Steel

==User Interaction Profile==

==User Interaction Profile==

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===Usage===

+

The two primary user interfaces are the power switch and the clamp nut.

−

''How does the user interface with the product(s)?''

+

*The power switch allows the user to cut power to the motor, apply power to the motor, and lock the grinder in an on position where power will be applied until removed.

−

The two primary user interfaces are the power switch and the wheel nut.

+

*The clamp nut allows the user to place different attachments on the angle grinder’s drive head and then secure them to prevent the disk from falling off.

−

• The power switch allows the user to cut power to the motor, apply power to the motor, and lock the grinder in an on position where power will be applied until removed.

+

Both interfaces are very intuitive and would require minimal thought process for the operator to use them.

−

• The wheel nut allows the user to place different attachments on the angle grinder’s drive head and then secure them to prevent the disk from falling off.

+

*The power switch has an O and and I marking power on and off respectively, with a small picture of a lock at the position where the power will locked on.

−

''How intuitive are the interfaces?''

+

*The clamp nut is threaded like a standard nut as it must be turned counter-clockwise to remove it, and turned clockwise to secure it and whatever disc may have been placed on the angle grinder. Placing the head is also very intuitive, as it slides right over the screw the wheel nut came off of.

−

• Both interfaces are very intuitive. The power switch has an O and and I marking power on and off respectively, with a small picture of a lock at the position where the power will lock on.

+

Because of the simplicity of these interfaces, the product requires minimal knowledge to use, as one can literally “flick the switch and go.” However, there are certain safety measures the user must first familiarize himself with. While they are not all intuitive (such as allowing the machine to fully accelerate before applying to the material, or fully decelerate before unplugging) they are quite simple, and require minimal user effort once the safety measures are known. In addition, specific materials and jobs come with their own safety measures, but just like the general safety tips, these are not a challenge once known.

−

• The wheel nut is a standard nut as it must be turned counter-clockwise to remove it, and turned clockwise to secure it and whatever head may have been placed on the angle grinder. Placing the head is also very intuitive, as it slides right over the screw the wheel nut came off of.

+

===Maintenance===

−

+

[[File:Brush_Maintenance.jpg|250px|thumb|right]]

−

''How easy is the product to use?''

+

−

+

−

The product requires minimal knowledge to use, as one can literally “flick the switch and go.” However, there are certain safety measures the user must first familiarize himself with. While they are not all intuitive (such as allowing the machine to fully accelerate before applying to the material, or fully decelerate before unplugging) they are quite simple, and require minimal user effort once the safety measures are known. In addition, specific materials and jobs come with their own safety measures, but just like the general safety tips, these are not a challenge once known.

+

−

+

−

''Is regular maintenance required?''

+

The primary form of maintenance the user will face is replacing the attachable heads, which is simply a matter of unscrewing the wheel nut, removing the old disk, putting the new one in, and replacing the wheel nut.

The primary form of maintenance the user will face is replacing the attachable heads, which is simply a matter of unscrewing the wheel nut, removing the old disk, putting the new one in, and replacing the wheel nut.

Line 312:

Line 335:

The only other forms of ordinary maintenance are replacing the brushes and main shaft bearing. Both of these are slightly more complicated.

The only other forms of ordinary maintenance are replacing the brushes and main shaft bearing. Both of these are slightly more complicated.

−

• The brushes can be replaced by removing the cover plates located to the rear of the motor (near the bottom of the tool). There is a screw that must be removed, but once it is and the cover plates are off, the brushes can be extracted, replaced, and the cover plates can be put back on.

+

*The brushes can be replaced by removing the cover plates located to the rear of the motor (near the bottom of the tool). There is a screw that must be removed, but once it is and the cover plates are off, the brushes can be extracted, replaced, and the cover plates can be put back on.

+

+

*The main shaft bearing is replaced by removing the guard, removing four screws in the grinder housing where the guard was clamped, and then removing the housing and bearing. The new bearing is then inserted, and the other parts are replaced.

−

• The main shaft bearing is replaced by removing the guard, removing four screws in the grinder housing where the guard was clamped, and then removing the housing and bearing. The new bearing is then inserted, and the other parts are replaced.

+

(All information for this section taken from Blackanddecker.com)

==Alternative Product Profile==

==Alternative Product Profile==

−

+

When comparing our angle grinder to alternative products that could perform the same jobs we considered several categories that were important to the overall ease of use and effectiveness of each product. In Table 4 our group provides a comparison of the DeWalt 4 1/2 in angle grinder and two other angle grinders that are about the same price and size.

As can be seen from Table 4, the DeWalt Angle Grinder is very average in terms of cost, power, and durability. However, it is the lightest of the angle grinders considered by a significant margin. This would be one of the major qualities to consider during dissection because our product most likely contains a high amount of plastic where other grinders would use heavier metals.

Introduction

Over the course of this project our group will be dissecting, analyzing, and reverse engineering the DeWalt 4 1/2 in Angle Grinder. This product is a commonly used tool in many machine shops for its versatility. Through the use of a motor and drive system along with varying attachments the angle grinder is able to grind, cut, and polish various materials. By analyzing how the angle grinder currently works at various system levels our group hopes to not only gain an understanding of what allows the angle grinder to do its jobs effectively, but also what could be done to improve it.

In this gate our group developed a plan to efficiently dissect our product and analyze its components. Part of developing this plan was first taking into account the qualities and capabilities of each group member, as well as the times they are available. The plan for dissection and group-member analysis can be found under Work Proposal. Once our group had created an initial assessment of each member's capabilities and the jobs that would need to be completed we created a tentative division of labor. Roles and associated expectations were assigned to each member based on what tasks they preferred as well as which tasks they were qualified for. This tentative division of labor can be found under Management Proposal. Finally, our group conducted a thorough evaluation and analysis of our product without first dissecting it. This initial inspection and analysis can both be found under the Product Archaeology section of this gate.

Project Management

In this section our group provides a self-evaluation of each member's capabilities and lays out our plan for completing this project. In addition, we provide the framework for how our group intends to function both through internal interaction and conflict resolution.

Work Proposal

Plan for assembly and disassembly

Our group plans to perform the disassembly October 10 and 12 in the lab. Given the relatively small size of our product, we do not expect the dissection process to take longer than these two three hour sessions. During the disassembly process we will have one member take pictures of the product after each step of the dissection and one member record a written description of each step. This will facilitate the eventual reassembly of the part. Once the product has been fully disassembled and analyzed, we will reassemble the product by putting the parts back together in the same order we took them apart. The same tools used for disassembly should suffice for this part. Our preliminary dates for completing the reassembly are November 19 and in the lab. The remaining jobs such as part analysis and written submissions will as a rule be completed two days before each gate is due. A timeline of our activities is provided in Figure 1 for reference.

Based on an initial assessment of the product's exterior and the fasteners in place, these are the tools we expect to need for reassembly and disassembly:

1/16”-1/8” Phillips Head and Flathead Screwdrivers

5/32”-1/4” Crescent Wrenches or Sockets w/ Socket Driver

4 mm-6 mm Crescent Wrenches or Sockets w/ Socket Driver

In addition, these are the tools our group may or may not need, depending on the nature of the internal components:

T-15-T-25 Torx wrenches

Needle Nose Pliers

Figure 1: Proposed Timeline of Events for Project

Analysis of Group Members

In this section our group provides a brief summary of each group member's skills and flaws relevant to the project. The primary traits we were concerned with were general experience with machines, experience with angle grinders, computer and solid modeling skills, people skills, and availability. We decided that these factors would provide an adequate idea of which parts of the project each group member would be best for, as well as helping us figure out which skills we would have to develop over the course of the project. This self-evaluation is provided in Table 1 below.

Table 1:Evaluation of Relevant Group Member Qualities

Group Member

Experience with machines

Experience with angle grinders

Computer and Solid Modeling Skills

People Skills

Availability

Ethan George

Has limited experience with machines

Has never operated an angle grinder before

Has limited computer skills: No solid modeling experience or skills

Works well with people

Very open schedule: readily available to work on project

Michael Halloran

Has worked extensively with gas powered machines

Has limited experience with angle grinders

Poor computer skills: Some solid modeling experience and basic skills

Decent people skills

Fairly open schedule: readily available to work on project

Zachary Picciano

Has worked extensively with machines

Has worked extensively with angle grinders

Good computer skills: Good solid modeling experience and skills

Decent people skills

Very busy schedule: needs advanced notice to work on project

Has no experience working with machines

Has no experience with angle grinders

Decent computer skills: No solid modeling experience or skills

Decent people skills

Moderately busy schedule: needs advanced notice to work on the project

Tharaka Gabadage

Has no experience with machines

Has no experience with angle grinders

Very poor computer skills: No solid modeling experience or skills

Poor people skills

Very busy schedule: Needs advanced notice to work on the project

Overall analysis of group

Our group currently possesses all of the skills it will need; however we are overly reliant on certain group members in certain areas. All of our members will need to familiarize themselves with the general function of an angle grinder. Also, those with decent or poor computer skills need to improve these in order to aid in communicating with other members and submitting work. There is no way to “fix” the limited availability of some group members, so we will instead have to work around this by accommodating meetings to their schedules and doing large portions of the work individually. This will also require our group to develop good electronic communication skills so that we do not waste time or fail to cover certain aspects of the project. Lastly, we will need to get at least one other person to learn about solid modeling, as having only one person with those skills will be crippling if he cannot get the work done (it should be noted the one member who currently has these skills has a very busy schedule). By improving in these areas, our group will be able to function effectively for the duration of this project.

Management Proposal

Work Distribution

The general rule for distributing work will be to first allow group members to volunteer for any part of a given gate that they feel they could best complete due to their specific skill set or group role. After this initial process, the Project Manager (see below) will assign any remaining tasks in a manner he feels most appropriate, using the same criteria as above, as well as considering how much work each person already has to do on the project.

Contact Information

Our group can be contacted at any time through Communication Liaison (see below) Michael Halloran. He may be emailed at mphallor@buffalo.edu or mikehalloran93@gmail.com (both forward to the same address, so there is no preference in which address to email), and will respond promptly with any information you may require, as well as inform the group about any emails he may receive.

Meeting Plan

Our group will be meeting on a specific set of days that we have already agreed to. All group members are expected to attend every meeting given that the schedule was created to accommodate each member's schedule. If however a member cannot attend for an unforeseen reason, they will be forwarded meeting minutes and asked for their position on any relevant votes. All other information on group meetings is provided in Table 2 below.

Table 2: Group Meeting Plan

Date and Time

Duration

Location

Reason for Meeting

Tasks to Accomplish at Meeting

October 10 at 6PM

3 Hours

Furnas Dissection Lab

To assign tasks for Gate 2 and begin the dissection of the angle grinder

Disassemble angle grinder, take photographs and create a log of each step

October 12 at 6PM

3 Hours

Furnas Dissection Lab

To complete the dissection of the angle grinder

Finish disassembling the angle grinder, take photographs and create a log of each step

October 25 at 5PM

1 Hour

Capen Library

To collectively review Gate 2 before submission

Read through all parts of the project, check for spelling and/or grammar mistakes, and verify that all parts were completed with a sufficient level of detail

October 27 at 5PM

1 Hour

Capen Library

To assign clarify and assign tasks for Gate 3

Go through Gate 3 assignment, divide jobs, and collectively discuss the interpretations of any tasks

November 14 at 5 PM

1 Hour

Capen Library

To collectively review Gate 3 before submission

Read through all parts of the project, check for spelling and/or grammar mistakes, and verify that all parts were completed with a sufficient level of detail

November 17 at 5PM

1 Hour

Capen Library

To assign clarify and assign tasks for Gate 4

Go through Gate 4 assignment, divide jobs, and collectively discuss the interpretations of any tasks

November 26 at 6PM

3 Hours

Furnas Dissection Lab

To assign tasks for Gate 4 and begin the reassembly of the angle grinder

Reassemble angle grinder, take photographs and create a log of each step

November 29

1 Hour

Capen Library

To collectively review Gate 4 before submission

Read through all parts of the project, check for spelling and/or grammar mistakes, and verify that all parts were completed with a sufficient level of detail

Group Roles

In order to facilitate group communication, conflict resolution, and overall project completion, our group has created the following roles and assigned group members to them based on the information provided in the self evaluation.

Project Manager (Ethan George)- The project manager will be responsible for assigning work to other group members as well as laying out a timeline for meetings. In addition to taking some tasks for himself, he will contact other group members regularly to make sure they are moving at a proper pace and try to prevent parts of the project from being overlooked. In addition, he will make the final decision on issues such as requirement interpretation, changes of schedule, and whether work submitted by other members is of high enough quality or not.

Communication Liaison (Michael Halloran)- The communication liaison will be responsible for being a reliable point of contact with the professors, as well as organizing and posting the group’s work through the wiki page. He will disseminate any information or feedback the professors provide and ask any questions the group has. Below, the contact information for the communication liaison is listed again:

mphallor@buffalo.edu

mikehalloran93@gmail.com

Technical Expert (Zachary Picciano)- The Technical Expert will be responsible for having an in depth understanding of the product’s function, structure, and components. He will through research and prior experience gain an in-depth understanding of these aspects so that he can lead the dissection and reassembly. On these parts of the project, the Technical Expert and NOT the Project Manager will have full authority as he will have the greatest knowledge of what needs to be done and how to do it safely. In addition, the Technical Expert will do any solid modeling of the product, although he will be working with the other members in describing what exactly must be drawn or designed.

Research Experts (Takur Phuyel and Tharaka Gabadage)- The research experts will be responsible for doing any research not already covered by the technical expert. In addition to completing tasks that are specifically research oriented, they will also look into any other questions that may arise over the course of the project. They will then be responsible for informing the group about their findings so that the entire group will have a clearer understanding of the project.

Conflict Resolution Plan

All group conflicts will be settled by a discussion of the disagreement at either the next meeting or a meeting scheduled by the project manager to specifically deal with urgent issues. Once the conflict has been discussed other group members will be allowed to suggest alternative solutions, and all group members will then vote on the course of action they most prefer. Individuals who ignore group decisions, do not complete the required work, or fail to attend meetings without a legitimate excuse will be worked around by delegating all significant assignments to other group members. As recourse the other group members will collectively give such individuals poor scores on the group evaluation at the end of the project.

Product Archaeology

This section contains our group's findings after performing background research on our product and performing an inspection without completing disassembly.

Development Profile

The first angle grinder developed by Flex Company consisted of an electric motor and a flexible shaft for grinding attachments.

The first angle grinder was developed by Flex Company in the late 1920s. While this angle grinder does not bear much resemblance to modern angle grinders, it was the first handheld tool to allow the user to perform grinding functions. The DeWalt Heavy Duty Angle Grinder family of products was later developed in the early 2000s (Flex-Tools.com). At this point in time the primary global and economic concerns for the angle grinder were the functionality and price point for the intended audience. These concerns are listed below:

Global: The DeWalt angle grinder was developed for countries with developed economies. The tasks angle grinders are intended to do, such as finishing wood, polishing doors, and removing weld seams, are not usually done in developing nations. In addition, a lack of reliable power grid would make the electric angle grinder inferior to those with other power sources.

Economic: The DeWalt angle grinder reduced cost by using less cast iron than traditional angle grinders and replacing many auxiliary parts with plastic. It also uses less power than other similar angle grinders in order to reduce electrical costs for the user. (cpometabo.com)

Our angle grinder is only intended for sale in North America, primarily the U.S. and Canada. This is because the product must undergo special testing for certification to be sold in Europe, and “DeWalt Europe” is a similar but different version of this product for sale there. (Blackanddecker.com)

The angle grinder was designed to make many household tasks easier. This product furthers that goal of the original angle grinders by making the angle grinder lighter weight and easier to use, which is ideal for both household use and extended use in a professional setting. The overall intended impact of this product was therefore to make grinding an easier task to accomplish.

Usage Profile

This user is using an angle grinder to sand a deck much faster than could be done with sand paper.

The intended use of the angle grinder is grinding various materials. In addition to grinding, multiple attachments can be fitted allowing the angle grinder to cut, sand, and polish. In combination with the ability to use a grinder almost anywhere, these array of functions make the angle grinder a great "all-purpose tool" for material removal. Angle grinders can be used for both home and professional uses, but this angle grinder was most likely designed with an emphasis on professional use. This is because the parent company of DeWalt (Black and Decker) already produces an array of cheaper product alternatives. DeWalt is instead a more expensive heavy duty brand, which suggests the intended customers were either professionals or home owners with hobbies (i.e. carpentry) that required a large amount of grinding.

The following is a list of the most common functions an angle grinder might perform in a professional setting.

With the use of various qualities of grinding disk an angle grinder can grind metal weld seams to make them smooth.

Cutting metal, concrete, and stone can be done by attaching a cut-off disk (usually with a diamond blade).

Sanding disks allow the user to sand wood quicker than with sand paper.

Polishing disks and wire brush disks allow the user to polish metal and remove corrosion, rust, and paint from metal.

These functions, along with other more obscure uses, are what make the angle grinder so versatile. It is one tool that allows the user to perform a wide array of tasks for a given job.
(All information for this section taken from Blackanddecker.com)

Energy Profile

The product uses AC electrical energy and rotational kinetic energy, which changes direction at the grinder head. Electricity is the only energy imported into the system, which is done by connecting the plug to any standard U.S. AC outlet. The electrical energy imported into the system is then transformed into rotational kinetic energy by an AC motor in the bottom of the tool. This motor drives the main shaft which in turn rotates a gear. This gear redirects the rotational kinetic energy by turning the axis of rotation 90º at the head of the grinder, which in turn delivers its rotational kinetic energy to the grinder’s disk and the object the tool is being used on. This flow of energy is summarized below in Figure 2.

(All information for this section taken from Thefamilyhandyman.com)

Figure 2: Energy Profile

Complexity Profile

Based on observation of the product, group members' collective experience with electronic motors, and our theory of how the angle grinder will work, we have determined that the following components are present in our product. Components in regular font are observable, and therefore definitely present in the product. Components in Bold are not clearly visible, but our reasons for believing these components are present is given alongside the component.

Power cord

Electric Motor:Based on the presence of a power cord and the fact the grinder outputs kinetic energy, it is safe to assume

Main shaft:There must be some component present to deliver power from the motor to the grinder head. We theorize a shaft is used to carry this energy.

Gear box

Backing Flange

Handle

Power Switch

Housing

Our method for assessing the complexity of the components was based on the number of parts we theorize will be present and the possible energy flows that may be associated with the component. Each of the components will therefore be rated on the following scale:

1: This component is very simple and only contains one part that either does not contain any energy flows, or only delivers simple energy flows.

2: This component is somewhat complex and may contain multiple parts or contains simple energy flow.

3: This component is very complex and contains multiple parts as well as complicated energy flows.

Based on this rating scale, our group has constructed Table 3, which contains all of the observable and theorized parts as well as the complexity of each part and a brief justification for this rating:

Table 3:Component Complexity

Component

Complexity Rating

Justification

Power Cord

2

The power cord consists of at least two parts: the rubber insulation and the copper wire which must branch off to any electrical components at some point. The power cord also allows electricity to flow through it, which is a fairly simple flow of energy.

Electric Motor

3

The electric motor must consist of several components including magnets, brushes, wire coils, and an armature. There is also a complex flow of energy as the electrical energy input into the system is converted to kinetic energy as an output.

Main Shaft

1

The main shaft would only consist of one part (the shaft) and would deliver a very simple form of energy; it would take rotational energy from the motor and deliver rotational energy to the gearbox.

Gear Box

3

The gearbox must contain multiple gears in order to take the rotational energy from the main shaft and turn it 90 degrees. In addition the gearbox must contain ball bearings in order to allow the free rotation of the helical gear. These many parts and the complex flow of energy make the gearbox a very complex component.

Backing Flange

1

The backing flange only consists of one part and that part only takes rotational energy from the gearbox and delivers it to whatever disk is put on the grinder.

Handle

1

The handle is only one piece and does not contain any energy flow.

Power Switch

2

The power switch must consist of at least two parts (the visible switch, and some bar that moves electrical contacts to start the motor). The switch takes a signal from the user and changes it into a signal to start or stop the electric motor. This makes the power switch a moderately complex part.

Housing

2

Even though the housing does not allow for any energy flows, it does contain several pieces that must be assembled properly in order to hold the functional components of the angle grinder in place.

The component interactions can be broken up into three main groups: the electrical interaction, the initial rotational interaction, and the output rotational interaction. These three groups and the complexities of their interactions are given below.

Electrical Interaction: The electrical component interactions consist of the switch, power cord, and electric motor. Moving the switch results in moving metal contacts that allow energy to flow into the electric motor when the switch is on, but not when it's off. These interactions are simple because they only contain simple energy flows and are very intuitive.

Initial Rotational Interaction: The initial rotational interactions consist of the electric motor, main shaft, and gear box. The electric motor takes the electrical energy supplied by the power cord and converts it into rotational energy by varying the flux in a coil in a magnetic field. This rotational energy is then delivered by the main shaft to the gear box. These component interactions are the most complex as it is the only place in the device where energy completely changes form. A significant part of our investigation of this product will include how these components interact to produce this initial kinetic energy.

Output Rotational Interaction: The output rotational interaction consists of the gear box and backing flange. This interaction will be fairly complex as the gearbox must take the rotational energy from the main shaft and redirect it, which will include the interactions of at least two gears. This redirected rotational energy will then be applied to the backing flange, which will then apply the rotational force to whatever attachment is being used on teh angle grinder.

The remaining components not addressed above do not interact with any other components in ways that contribute to the overall function of the angle grinder (i.e. Handle to housing interaction). The complexity of these component interactions are therefore trivial and non-applicable.

Material Profile

The clearly visible materials on our product

Based on coloration, texture, and function where applicable, our group has determined that the clearly visible parts of the angle grinder are made of the following materials:

Rubber (cord)

Copper (cord wire)

Steel (guard and backing flange/interior gear box)

Plastic (housing and power switch)

Aluminum (exterior gear box)

Our group also theorizes that magnetic iron must be present in order for the motor to function. An electric motor is driven by the force of magnetism on a current carrying loop (Experimental Researches in Electricity). All other components that we expect to find will be made of materials already present in the exterior:

Main Shaft:

Steel Shaft

Copper Wire Coil

Plastic Fan

Wires: Copper and Plastic/Rubber insulation

Gears: Steel

User Interaction Profile

Usage

The two primary user interfaces are the power switch and the clamp nut.

The power switch allows the user to cut power to the motor, apply power to the motor, and lock the grinder in an on position where power will be applied until removed.

The clamp nut allows the user to place different attachments on the angle grinder’s drive head and then secure them to prevent the disk from falling off.

Both interfaces are very intuitive and would require minimal thought process for the operator to use them.

The power switch has an O and and I marking power on and off respectively, with a small picture of a lock at the position where the power will locked on.

The clamp nut is threaded like a standard nut as it must be turned counter-clockwise to remove it, and turned clockwise to secure it and whatever disc may have been placed on the angle grinder. Placing the head is also very intuitive, as it slides right over the screw the wheel nut came off of.

Because of the simplicity of these interfaces, the product requires minimal knowledge to use, as one can literally “flick the switch and go.” However, there are certain safety measures the user must first familiarize himself with. While they are not all intuitive (such as allowing the machine to fully accelerate before applying to the material, or fully decelerate before unplugging) they are quite simple, and require minimal user effort once the safety measures are known. In addition, specific materials and jobs come with their own safety measures, but just like the general safety tips, these are not a challenge once known.

Maintenance

The primary form of maintenance the user will face is replacing the attachable heads, which is simply a matter of unscrewing the wheel nut, removing the old disk, putting the new one in, and replacing the wheel nut.

The only other forms of ordinary maintenance are replacing the brushes and main shaft bearing. Both of these are slightly more complicated.

The brushes can be replaced by removing the cover plates located to the rear of the motor (near the bottom of the tool). There is a screw that must be removed, but once it is and the cover plates are off, the brushes can be extracted, replaced, and the cover plates can be put back on.

The main shaft bearing is replaced by removing the guard, removing four screws in the grinder housing where the guard was clamped, and then removing the housing and bearing. The new bearing is then inserted, and the other parts are replaced.

(All information for this section taken from Blackanddecker.com)

Alternative Product Profile

When comparing our angle grinder to alternative products that could perform the same jobs we considered several categories that were important to the overall ease of use and effectiveness of each product. In Table 4 our group provides a comparison of the DeWalt 4 1/2 in angle grinder and two other angle grinders that are about the same price and size.

Table 4:Comparison of DeWalt Angle Grinder and Alternative Products

Factor

DeWalt 4 1/2 in Angle Grinder (Blackanddecker.com)

Milwaukee 11 Amp 5 in Angle Grinder (Homedepot.com)

Black and Decker G950 4 1/2 in Angle Grinder (Blackanddecker.com)

Weight

4.6 lb

6.88 lb

7.0 lb

Warranty

3 Years

5 Years

2 Years

Control

One Speed

Variable Speed

Variable Speed

Top Speed

11000 RPM

11000 RPM

10000 RPM

Power

800 W

860 W

650 W

Cost

$89

$99

$86

As can be seen from Table 4, the DeWalt Angle Grinder is very average in terms of cost, power, and durability. However, it is the lightest of the angle grinders considered by a significant margin. This would be one of the major qualities to consider during dissection because our product most likely contains a high amount of plastic where other grinders would use heavier metals.